TWI517188B - Superconducting coils and superconducting magnets - Google Patents

Description

Superconducting coil and superconducting magnet

The present invention relates to superconducting coils and superconducting magnets.

According to Japanese Laid-Open Patent Publication No. Hei 11-186025, it is disclosed that the first and second pie-shaped coils (Pancake Coils) are laminated, and the middle and the second pie-shaped coils are disposed between the first and second pie-shaped coils. The superconducting coil of the cooling plate. The cooling plate is connected to the cooling head by means of a heat conducting rod.

In the technique described in the above publication, the first and second coils (coil portions) to be laminated are connected to the cooling head by a cooling plate (heat transfer plate) and a heat transfer rod. The relative position between the coil portion and the cooling head varies for various reasons. The reason for this is, for example, a difference in thermal expansion and contraction, vibration caused by an air compressor for driving the cooling head, magnetic interaction between the coil portion and a subject to which a magnetic field is applied by the coil portion, and the like. Due to the change in the relative position due to this, the coil portion applies a load to the cooling head.

In order to efficiently cool the coil portion, it is necessary to reduce the thermal resistance of the heat transfer plate. As a simple solution to this purpose, it is conceivable to thicken the thickness of the heat transfer plate. However, if the thickness of the heat transfer plate is simply increased, the relative position between the coil portion and the cooling head does not easily change, and the load applied to the cooling head by the coil becomes large. In general, the cooling head is weak against the load from the outside, and if the load is excessively large, the cooling head may malfunction.

Here, an object of the present invention is to provide a superconducting coil and a superconducting magnet which can prevent a failure of a cooling head and improve cooling efficiency of a coil portion.

The superconducting coil of the present invention has a coil portion, a cooling head, and a heat transfer portion. The coil portion is formed by winding a superconducting wire. The cooling head is used for cooling the coil portion. The heat transfer portion connects the coil portion and the cooling head to each other. The heat transfer portion has a first heat transfer plate and a second heat transfer plate. The first heat transfer plate is attached to the coil portion at the first position. The second heat transfer plate is attached at a second position away from the first position. The first heat transfer plate is thicker than the second heat transfer plate.

According to the superconducting coil of the present invention, the thermal resistance can be reduced by making the first heat transfer plate later. Thereby, the heat generated in the coil portion can be removed efficiently by the cooling head. Further, by making the second heat transfer plate thinner and making the flexibility larger, the second heat transfer plate can be interposed to reduce the load received by the coil portion of the cooling head. Thereby, it is possible to prevent the load applied by the coil portion from causing malfunction of the cooling head. As described above, it is possible to prevent the failure of the cooling head while improving the cooling efficiency.

The coil portion may have an end portion through which the magnetic flux passes. In this case, the first position is closer to the end portion of the coil than the second position.

As a result, the first heat transfer plate having a relatively small thermal resistance can efficiently remove heat from the end portion of the coil portion which is likely to be generated by the heat generated by the vertical magnetic field.

The first heat transfer plate may be formed by laminating a plurality of single-layer sheets.

As a result, the flexibility of the first heat transfer plate is increased as compared with the case where the first heat transfer plate is formed of one single-layer plate, so that the cooling head that is transmitted through the first heat transfer plate can be reduced. The load from the coil portion. Thus, it can be prevented The load applied by the coil portion causes a malfunction of the cooling head.

The heat transfer portion has a fixture. The fixture is attached to the cooling head and holds the first heat transfer plate and the second heat transfer plate together.

Thereby, it is possible to suppress the thermal resistance while achieving the connection to the cooling head of each of the first and second heat transfer plates in accordance with a simple structure.

The cooling head has an end that can be cooled. The end of the cooling head has an end surface and a side surface surrounding the end surface. The fixture is in contact with the side of the cooling head.

Thereby, the end portion of the cooling head can be utilized more effectively, and the cooling efficiency can be improved.

The superconducting magnet of the present invention has the above-mentioned superconducting coil and a heat insulating container. The insulated container houses the superconducting coil.

According to the superconducting magnet of the present invention, it is possible to prevent the failure of the cooling head while improving the cooling efficiency.

The foregoing and other objects, features, aspects and advantages of the present invention are disclosed in the claims

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to Fig. 1, a superconducting magnet 100 of the present embodiment has a superconducting coil 91, a heat insulating container 111, a cooling device 121, a hose 122, an air compressor 123, a cable 131, and a power source 132. The heat insulating container 111 houses the superconducting coil 91. In the present embodiment, the magnetic field application region SC for accommodating a sample (not shown) to which a magnetic field is applied is provided in the heat insulating container 111.

2 and 3, the superconducting coil 91 has a coil portion 10, a cooling head 20, a heat transfer portion 30, and a core portion 81. The heat transfer portion 30 has a heat transfer plate group 31 and a fixture 32. The heat transfer plate group 31 is composed of heat transfer plates 31a to 31e.

The coil portion 10 is formed by winding a superconducting wire 14 (Fig. 6) and is used to generate a magnetic flux MF. Further, the coil portion 10 has an end portion through which the magnetic flux MF passes (the upper end or the lower end of FIG. 2). Further, the coil 10 has double-pancake coils 11a to 11m. The double-pancake coils 11a-11m are arranged in this order. The axial direction Aa (Fig. 2) corresponds to the stacking direction, and the radial direction Ar corresponds to the direction perpendicular to the stacking direction.

The cooling head 20, which is used by the cooling coil unit 10, has a coolable end portion 21, and a connecting portion 21 and a connecting portion 22 of the cooling device 121 (Fig. 1).

Each of the heat transfer plate groups 31 is attached to the coil portion 10. The fixture 32 is mounted to the end 21 of the cooling head 20. The fixture 32 holds the heat transfer plate group 31. Among the heat transfer plate group 31, the heat transfer plate 31a to the heat transfer plate 31e are directly laminated to each other. With such a configuration, the heat transfer portion 30 connects the coil portion 10 and the cooling head 20 to each other.

The relative position between the coil portion 10 and the cooling head 20 varies for various reasons. The reason for this is, for example, a difference in thermal expansion and contraction, vibration caused by the air compressor 123 (FIG. 1) for driving the cooling head 20, magnetic interaction between the coil portion 10 and a sample to which a magnetic field is applied by the coil portion 10, and the like. This variation causes the load applied from the coil portion 10 to the cooling head 20 to increase. . The load that the cooling head 20 can withstand, for example, up to 100 (N).

The coil portion 10 has a configuration in which a heat transfer plate and a pie-shaped coil are alternately laminated in a portion to be attached to the coil portion 10 of the heat transfer plate group 31. The heat transfer plates 31a are attached to the respective positions of the double-cake coils 11a and 11m at both ends of the coil portion 10. The heat transfer plate 31b is mounted between the double-cake coils 11a and 11b and the respective positions between the double-cake coils 11m and 111. The heat transfer plate 31c is mounted between the double-cake coils 11b and 11c and the respective positions between the double-cake coils 111 and 11k. The heat transfer plate 31d is mounted between the double-cake coils 11c and 11d and the respective positions between the double-cake coils 11k and 11j. The heat transfer plate 31e is mounted between the double-cake coils 11e and 11f, and between the double-cake coils 11j and 11i, and the positions between the double-cake coils 11f and 11g.

In other words, the heat transfer plates 31a to 31e are attached to the position of the coil portion 10 closer to the end portion in this order. Further, each of the heat transfer plates 31a to 31e is attached to a position where the coil portions 10 are apart from each other.

The material of the heat transfer plates 31a to 31e is preferably a material having high thermal conductivity and flexibility, and for example, aluminum (Al) or copper (Cu) may be used. The purity of Al (or Cu) is preferably 99.9% or more.

The heat transfer plates 31a to 31e may have a bent portion FD so as to extend to the fixture 32.

The fixture 32 has members 32a and 32b and screws 34a and 34b. The screw 34a is provided in such a manner as to adjust the gap between the members 32a and 32b. The gap between the members 32a and 32b sandwiches the heat transfer plate group 31, and the heat transfer plate group 31 is held by the fixing member by tightening the screw 34a. 32. That is, the heat transfer plates 31a to 31e are collectively held by the fixture 32. The screw 34b is provided in such a manner that each of the members 32a and 32b locks the side surface SD of the end portion 21 of the cooling head 20. Thereby, the fixture 32 is attached to the end portion 21 of the cooling head 20.

Referring to Figs. 4 and 5, the double-cake coil 11a has pie-shaped coils 12a and 12b which are laminated to each other. The winding direction Wa of the superconducting wire 14 of the pie-shaped coil 12a is opposite to the winding direction Wb of the superconducting wire 14 of the pie-shaped coil 12b. The end portion ECi of the superconducting wire 14 on the inner peripheral side of the pie-shaped coil 12a is electrically connected to the end portion ECi of the superconducting wire on the inner peripheral side of the pie-shaped coil 12b. Thereby, between the end portion ECo of the superconducting wire 14 on the outer peripheral side of the pie-shaped coil 12a and the end portion ECo of the superconducting wire 14 on the outer peripheral side of the pie-shaped coil 12b, the pie-shaped coils 12a and 12b are connected in series to each other. .

Each of the double-cake coils 11b to 11m also has the same configuration as the double-cake coil 11a. The end portions ECo of the adjacent ones of the double-cake coils 11a to 11m are electrically connected to each other. Thereby, the double-cake coils 11a-11m are mutually connected in series.

Referring to Fig. 6, the superconducting wire 14 has a thickness Dt of a dimension in the thickness direction At, and a width Dw of a dimension in the axial direction Aa, and extends in the extending direction Ae. The wide width Dw is larger than the thickness Dt, so that the superconducting wire 14 has a strip surface SF of a wide width Dw. The superconducting wire 14 has a characteristic that the AC loss increases as a vertical magnetic field (vertical magnetic field) is applied to the strip surface SF.

For example, the thickness Dt is about 0.2 mm, and the width Dw is about 4 mm. In addition, for example, the superconducting wire 14 has a Bi-system super extending in the extending direction. a conductor, and a sheath covering the superconductor. The protective cover is formed, for example, of silver or a silver alloy.

Referring to Fig. 7, the end portion 21 of the cooling head 20 has an end surface BM and a side surface SD surrounding the end surface BM. The cooling head 20 has, for example, a cylindrical shape.

Referring to Fig. 8, the heat transfer plate 31a may be a laminated plate having a thickness T31a, and preferably a single layer plate 11 having the same thickness is laminated. Alternatively, the heat transfer plate 31a may be a single layer plate having a thickness T31a. The same applies to each of the heat transfer plates 31b to 31d (Fig. 2). The thickness of each of the heat transfer plates 31a to 31d is larger as the end portion (the upper end or the lower end of Fig. 2) of the coil portion 10 is larger. When the laminated plates are used as the heat transfer plates 31a to 31d, the thickness of the heat transfer plates 31a to 31d can be adjusted, for example, by the number of the single-layer plates 11 constituting each of the laminated plates. In this case, the number of layers of each of the heat transfer plates 31a to 31d is larger as the end portion closer to the coil portion 10.

The thickness of each of the single-layer sheets 11 is preferably 1 mm or less, and more preferably 0.5 mm or less, in order to secure sufficient flexibility.

Referring to Fig. 9, the heat transfer plate 31e is a single-layered plate having a thickness T31e smaller than the aforementioned thickness T31a. Preferably, the heat transfer plate 31e, as shown in Fig. 9, is composed of a single single layer plate 11.

Referring to Fig. 10, instead of the heat transfer plate 31a (Fig. 3) described above, a heat transfer plate 31aV in which insulating portions 41 and 42 for suppressing eddy current loss are inserted may be used. The insulating portion 41 is inserted into a slit formed in the heat transfer plate 31aV along the diameter direction of the coil portion 10. The insulating portion 42 is inserted into a slit formed in the heat transfer plate 31aV along the circumferential direction of the coil portion 10. The material of the insulating portions 41 and 42 is, for example, glass fiber reinforced plastic (GFRP).

According to this embodiment, the heat transfer plate group 31 has a first heat transfer plate and a second heat transfer plate which is thinner than the first heat transfer plate. For example, when the heat transfer plate 31a is the first heat transfer plate, each of the heat transfer plates 31b to 31e corresponds to the second heat transfer plate. Alternatively, if the heat transfer plate 31b is the first heat transfer plate, each of the heat transfer plates 31c to 31e corresponds to the second heat transfer plate. By making the first heat transfer plate thicker than the second heat transfer plate, the thermal resistance of the first heat transfer plate can be reduced. Thereby, the heat generated in the coil portion 10 can be removed efficiently by the cooling head. Further, by making the second heat transfer plate thinner and making the flexibility larger, the second heat transfer plate can be interposed to reduce the load received by the coil portion 10 on the cooling head. Thereby, it is possible to prevent the load applied by the coil portion 10 from causing malfunction of the cooling head 20. As described above, it is possible to prevent the failure of the cooling head 20 while improving the cooling efficiency.

Further, a first heat transfer plate whose heat resistance is reduced by a thick thickness is attached to a position close to the end portion of the coil portion 10. As a result, the first heat transfer plate having a relatively small thermal resistance can efficiently remove heat from the end portion of the coil portion 10 which is likely to be generated by the heat generated by the vertical magnetic field.

The first heat transfer plate may be formed by laminating a plurality of single-layer sheets. Thereby, the flexibility of the first heat transfer plate is increased as compared with the case where the first heat transfer plate is constituted by one single-layer plate, so that the cooling head 20 that has passed through the first heat transfer plate can be reduced. The load from the coil portion 10. Thereby, it is possible to prevent the load applied by the coil portion 10 from causing malfunction of the cooling head 20.

Further, the fixture 32 is attached to the cooling head 20 and holds the heat transfer plates 31a to 31e together. Thereby, the connection of the heat transfer plates 31a to 31e to the cooling head 20 can be made into a simple structure while suppressing thermal resistance.

Further, the fixture 32 is in contact with the side surface SD of the cooling head 20. Take this The end portion 21 of the cooling head 20 can be utilized more effectively, and the cooling efficiency can be improved.

Example 1

The inventors simulated the heat generated in each of the double-cake coils 11a to 11m constituting the coil portion 10. Further, the temperature difference between each of the double-cake coils 11a to 11m and the fixture 32 attached to the cooling head 20 was also simulated. This double-cake coil with a large temperature difference becomes higher temperature. Further, the temperature of the double-cake coils 11a to 11m is the value of the side (the right side surface of the coil portion 10 in Fig. 2) from which the heat transfer plate group 31 is drawn.

The heat transfer plate group 31 (Fig. 2) was an Al plate having a thickness of 0.5 mm. As the heat transfer plates 31a to 31d, a laminated plate formed by laminating an Al plate is used. The number of layers of the heat transfer plates 31a to 31d is 7, 5, 3, and 2, respectively. As the heat transfer plate 31e, a single layer plate of an Al plate is used. As the material of the Al plate, aluminum having a purity of 99.999% was used. Between the coil portion 10 and the fixture 32, the width (the dimension in the longitudinal direction of Fig. 10) of each of the heat transfer plates 31a to 31e is 50 mm, and the length (the dimension in the lateral direction of Fig. 10) is 200 mm.

The simulation results are shown below.

The closer the double-cake coils 11a to 11m are to the end portion of the coil portion 10 (the closer to the uppermost row or the lowermost row in Table 1), the larger the heat becomes. The reason for this is that the magnetic flux direction of FIG. 2 can be known, and the vertical magnetic field due to the end portion closer to the coil portion 10 becomes larger.

The temperature difference between each of the double-cake coils 11a to 11e is about 10 (K), and there is no big difference. In short, even if there is a large difference in the heat of each of the double-cake coils 11a to 11e, the temperature difference between the double-cake coils 11a to 11e can be suppressed.

Further, a simulation of the thermal resistance of each of the heat transfer plate group 31 and the fixture 32 was performed. Among the fixtures 32 (Fig. 2), the portions of the members 32a and 32b that hold the heat transfer group 31 have a thickness of 42 mm and a length of 50 mm. Further, the material of the fixture 32 is copper. Result, pass The thermal resistance of the hot plate group 31 is 0.055 (K/W), and the thermal resistance of the fixture 32 is 0.005 (K/W). That is, the thermal resistance caused by the fixture 32 can be made sufficiently small.

Example 2

This example simulates the load applied to the cooling head 20 when the distance between the coil portion 10 and the cooling head 20 is changed by 1 mm. This simulation is for investigating the influence of the use of the laminated plate in the heat transfer plate group 31. Therefore, each of the simulation condition heat transfer plates 31a to 31e has the same configuration.

Further, in the present simulation, as the heat transfer plate group 31, in addition to the case of using the aluminum plate described above, a simulation using a copper plate was also performed. There are three conditions for the number of layers. The first condition is a laminate number of 6, corresponding to a laminated board of six single-layer sheets having a thickness of 0.5 mm. The second condition is a laminated number of 3, which corresponds to a laminated board having three single-layer sheets having a thickness of 1.0 mm. The third condition is a laminated number of 1, corresponding to a single-layered plate having a thickness of 3.0 mm. The results are shown below.

As a result, it was found that the load applied to the cooling head 20 can be reduced by ensuring the entire thickness of each heat transfer plate (maintained at a thickness of 3 mm in this case) and increasing the number of layers.

The invention is described in detail above, but is not intended to limit the scope of the invention, and the scope of the invention is limited by the scope of the claims.

10‧‧‧ coil department

11a~11m‧‧‧Double-pancake Coils

11‧‧‧Single board

12a, 12b‧‧‧Cupcake Coil

14‧‧‧Superconducting wire

20‧‧‧Cool head

21‧‧‧ End

22‧‧‧Continuation Department

30‧‧‧Transfer Department

31‧‧‧Transfer plate group

31a~31e, 31aV‧‧‧ heat transfer plates

32‧‧‧ Fixtures

32a, 32b‧‧‧ components

41, 42‧‧‧Insulation Department

81‧‧‧ core

91‧‧‧Superconducting coil

100‧‧‧ superconducting magnet

111‧‧‧Insulated container

121‧‧‧Cooling device

123‧‧‧Air compressor

132‧‧‧Power supply

BM‧‧‧ end face

FD‧‧‧Folding Department

SC‧‧‧Magnetic field application area

SD‧‧‧ side

SF‧‧‧ belt surface

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view schematically showing the configuration of a superconducting magnet according to an embodiment of the present invention.

Fig. 2 is a view schematically showing the configuration of a superconducting coil of the superconducting magnet of Fig. 1, and is a cross-sectional view taken along line II-II of Fig. 3.

Fig. 3 is a plan view schematically showing the configuration of the superconducting coil of Fig. 2;

Fig. 4 is a perspective view schematically showing the configuration of a double-pancake coil having the superconducting coil of Fig. 2;

Fig. 5 is a schematic cross-sectional view taken along line V-V of Fig. 4.

Fig. 6 is a partial perspective view schematically showing the configuration of a superconducting wire used in the double-pancake coil of Fig. 4.

Fig. 7 is a partial perspective view schematically showing the configuration of a cooling head provided in the superconducting coil of Fig. 2;

Fig. 8 is a partial cross-sectional view showing a schematic configuration of a heat transfer plate composed of a laminated plate of the superconducting coil of Fig. 2;

Fig. 9 is a partial cross-sectional view schematically showing the configuration of a heat transfer plate composed of a single-layered plate of the superconducting coil of Fig. 2;

Fig. 10 is a plan view schematically showing a configuration of a superconducting coil according to a modification.

10‧‧‧ coil department

11a~11m‧‧‧Double-pancake Coils

20‧‧‧Cool head

21‧‧‧ End

22‧‧‧Continuation Department

30‧‧‧Transfer Department

31‧‧‧Transfer plate group

31a~31e‧‧‧heat transfer plate

32‧‧‧ Fixtures

32a, 32b‧‧‧ components

34a‧‧‧screw

81‧‧‧ core

91‧‧‧Superconducting coil

BM‧‧‧ end face

FD‧‧‧Folding Department

SD‧‧‧ side

MF‧‧‧Magnetic Beam

Claims (6)

A superconducting coil (91) comprising: a coil portion (10) in which a plurality of coils are stacked along a stacking direction, wherein each of the plurality of coils is formed by winding a superconducting wire (14), the coil portion An end portion is provided at both ends in the stacking direction, and further includes a cooling head (20) for cooling the coil portion, and a heat transfer portion (30) that connects the coil portion and the cooling head to each other; and the heat transfer portion The first heat transfer plate (31a) attached to the coil portion at the first position and the second position at which the coil portion is separated from the first position in the stacking direction of the plurality of coils are mounted. a second heat transfer plate (31e); the first heat transfer plate is thicker than the second heat transfer plate, and the first position is located between the laminated plurality of coils or the end portion of the coil portion The second position is located between the plurality of laminated plurality of coils; a distance from the end portion to the second position in the stacking direction, and a distance from the end portion to the first position in the stacking direction The distances are different. The superconducting coil according to claim 1, wherein the coil portion has an end portion through which a magnetic flux (MF) passes, and the first position is closer to the end portion than the second position. The superconducting coil according to claim 1 or 2, wherein the first heat transfer plate is formed by laminating a plurality of single-layer plates (11). The superconducting coil of claim 1 or 2, wherein the heat transfer portion has a cooling head attached thereto and holds the foregoing A heat transfer plate and a fixture (32) of the second heat transfer plate. The superconducting coil of claim 4, wherein the cooling head has a coolable end portion (21), the end portion has an end surface (BM) and a side surface (SD) surrounding the end surface, the fixing device and the cooling The aforementioned side contact of the head. A superconducting magnet (100) characterized by comprising a superconducting coil of claim 1 and a heat insulating container (111) for housing the superconducting coil.